Machine for grinding multifocal lenses.



C. A. HOHMAN;

MACHINE FOR GHlNBING MULTIFDCAL LENSES. APPLiCATIGN mm MAY 1?. I913.

Paternal Get. 2, 1917.

3 SHEETS-SHEET L IIZLIIIIIJ C. A. HOFFMAN.

MACHINE FOR GRINDING MULHFUCM LENSES.

APPucmou HLED mun. 1913.

1,241,628. Patented Oct. 2, 1917.

3 SHEETSSHEET 2;

Wifiwwes. IIIUGZ' Eur 6. Kan-M I 0w. f a fimml/ L V F9 his Iii 01mg? C. A. HOFFMAN.

MACHSNE FOR GBCNDING MULTIFOCAL LENSES.

APPLICATION FILED MAY 1?. 121a.

Patented 0st. 2, 1917.

3 SHEETS-SHEET 3.

l z /w mrfiwlf [twenlor/ C. (L. J f nan luls A omleap" i i 0' CHARLES A. HOFFMAN, 01F MINNEAPOLIS, MQINNESOTA.

MACHINE FOR GRINDING MUL'I'IFOGAL LENSES.

Specification of Letters Iatent.

Patented Oct. 2, 1917.

Application filed Kay 17, 1913. Serial No. 768,289.

I?) all whom it may concern:

Be it known that I, (hmRLns A. Horr- MAN, a citizen of the United States, residing at l\linneapolis, in the county of Henncpin and State of Minnesota, have invented certain new and useful Improvenients in Machines for Grinding Multifocal Lenses; and I do hereby declare the following to be a full, clear, and exact description of the'invention, such as will enable others skilled in the art to which it appertaius to make and use the same.

My invention has for its object to provide an improved lens grinding machine especially adapted for use in grinding bifocal or multifocal lenses, suclr as used in spectuclcs, eye glnsscs. and the like. (:rcucrally stated, the invention consists of the novel devices and combinations of devices hereinafter described and clelincd in the claims.

In the accompanying drawings which illustrate the invention, like character indicate like parts throughout the several views.

Referring to the drawings,

Figure 1 is a plan view with some parts broken away and with some parts removed, showing the improved machine v F ig. 2 is a. view partly in side elevation and vpartly in vertical section, and with some parts. broken away, showing the improved grinding ,niachinc;

Fig. 3 is a bottom plan view of the machine, some parts being broken away;

F ig. l is a side elevation showing the lower portion of the machine;

F lglxfi is a vertical section on the line a;-.2: onFig. 2, some parts being removed; Fig. (3 is a detail in section on the, line L' -flZ on Fig. 1, some parts being broken away; and

Fi'g. T is an enlarged section taken on the line re -w on Fig. 5.

In the construction illustrated, the various parts of the machine are'supported directly or indirectly on the framework 1 having a table 2. with hearing pedestals 3-4 and 5-6. r. y

Pivotally mounted on the upper ends of the edestals 3 4, are short. levers 78 provided at their rear ends with handle bar extensions 7 and 8, respectively, that are capable of vertical movements in respect to the saidlevers. levers 7-8 are connected by links 9 to wrist pins 10 carried by crank disks 11 secured on the upper ends of upright countershailts enlarged lower ends 310 The front ends of the said i 12 journuled in the pedestals 5-6 and eX- tended downward through the table 2. To make the wrist pins 10 capable of variable throw, they are adjustably connected to the crank disks 11, by clamping bolts 13, the heads of which work in undercut diametrical channels 14 formed in the face of the said disks. The bolts 13 are provided with claniping nuts 15 (sec particularly Fig. 6), by means of which, the said wrist pins 10 may be secured in their different adjustments.

In Fig. ,5, a, bifocal lens is indicated by the character y. The convex surface of this lens is cemented, or otherwise temporarily secured to the concave upper face of the face plate 16 secured on the upper end of a spindle 17 journaled in a'suitable hearing 18 on the table 2, and provided at its lower end with e-gr'oove pulley 19 and hand wheel 20. The spindle 1'2 and face plate 16 are given a constant rotary motion, preferably from a small electric motor 21, through connections presently to be described. The said motor 21 is shown as suitably secured to the underside of the table 2 and its armature shaft 21 is journaled to snitable bearings on the frame 1, and is provided with groove pullcys'22, 23, 24 and 25. A belt 26 runs over the pulley 23 and over the pulley 19 on the said spindle 17. i

Belts 27 run over the pulleys 22 and '25 and over groove pulleys 28 on the lower ends of the crank disk shafts 12. v

Joni-na led, as shown, in hearing brackets 29, on the lever handle bars 7 and 8 and capable of vertical movements therethrough are spindles .30, preferably constructed with having depending spherical heads 31 and diametrically opposite; pins 32. The spherical heads 31 are rigidly secured to the lower ends 30* but the pins 32 are loose for vertical movements therein. Grinding, tools in the form of disks 33 are mounted for wabbling movements on the heads 31 and ,are provided with diamctricall opposite perforations or indentations in w ihthe ends of the cooperating pins 32 are Seated the pins 32 act as driving i disks 33 to rotate with the 'sp h at the same time, the said (1 :1; mitted to wobble or oscillate to a selves to the curve of the lens surface which is being ground thereby. One of these grinding disks, to-wit, the disk shown at the right in Fig. 5, is adapted to grind the distance surface of the lens while the other disk is adapted to grind the reading surface of the said lens. 'lhes disks, by oscillatory movements of the spindlrs 30, are, caused to travel back and forth over the surface which they are intended to grind, and this movement may be very accurately regulated by proper adjustments of the throws of the coiiperating wrist pins 10 of the crank disks 1]. The said crank disks are arranged to rotate in the same direction, so that the grinding disks will move simultaneously in the same direction rather than toward and from each other. which latter movement would cause a conflict by engagement of the two grinding disks at extreme inward movements.

The grinding disks 33 are held or pressed downward against the lens, partly by gravity and partly by the action of the coiled springs 34, which, as shown, are attached to the table 2 and to' the outer ends of the lever handle bars 7.

The bearing brackets 29 in the lever handle bars 7 and 8*, are provided with .recesses to receive grooved pulleys 35, through which the spindles 30 work vertically. The spindles 30 are provided with long key-ways 31' (see Fig. 5) that are engaged by key lugs 37 on the pulleys 35 (see Fig; 7).

Driving bolts 58 run over the pull ys 35, over idle guide wheels 39 journale'd to the sides of the levers 7-8, and under groove pulleys ll) carried by a counter-shaft 4 1 journalcd in suitable hearings on the frame 1. The counter shaft 41 is driven from the motor armature shaft 21.", through a belt 42 which runs over the pulley 24 and over a pulley 43 on the said counter shaft. The table 2 is provided w'th segmental clearance passages 44 (see Fi s. 1 and 2) through which the vertically extended portions of the driving bolts 38 a re arranged to pass.

When the machine above described is in action. it is evident that the face plate 16 and the lens y carried thereby, and both of the {:rinding disks which are operative on the ens, will be constantly rotated on their own axes, and'at the same time, the said grinding disks will be oscillated so that the one will travel over the entire distance surface ol the lens and the other will travel v r the entire reading surface of the lens. The oscillatory or traveling move menls of the two grinding disks should be so nicely regulated that the one will travel just, to. but. not at all lieypnd the surface that is heinggronnd or polished by the other grinding disk. Also, it is of the greatest importance to note that while the grinding actions of the two disks are independent, one of the other, they may be performed simultaneously without interference, one with the action of the other. It will also be re-' niemberrd that oscillatory movement or travel of the two grinding disks may be in dependently regulated.

Fig. 5 shows the proper adjustment of the grinding spindles for grinding both the near vision and the long vision zones of the lens. Fig. 1 does not, however, show such. adjustments, but it is evident that such adjustment may be accomplished by proper setting of the crank links 9 in respect to the crank disks 1]..

What I claim is:

1. A machine for grinding multifocal lenses comprising two oscillatory spindle supports, rotary spindles carried by said supports and provided each with its own grinding tool for operation on different zones of the lens, the said spindles having independentv actuating means including pullcys on the said spindles, and one of said spindles being shorter than the other and terminating below the pulley of the longer spindle.

2. A machine for grinding multifocal lenses comprising two oscillatory spindle supports, rotary spindles carried by said supports and provided each with its own grinding tool for operation on different zones of the lens, the said spindles having independent actuating means including pulleys on the said spindles, one of said spindles being shorter than the other and terminating below the pulley of the longer spindle, and independently driven variable throw crank connections for oscillating said spindle supports substantially as described.

3. A machine for grinding multifocal lenses, comprising two oscillatory spindle supports. rotary spindles carried by said' supports andprovided each with its own grinding tool for operatin zones of the lens. the said s indles having independent actuating means associated with the spindles, one of said spindles being shorter than the other and terminating be-- low the actuating means for the longer spindle.

In testimony whereof I allix my signature in presence of two witnesses.

(HARLES A. HOFFMAN. Witnesses RAY NOLANI), Grier W. Swnnnmmnd,

on different 

